The present invention relates to a power transfer mechanism control device controlling a power transfer mechanism which is mounted on a vehicle including an automatically stoppable and automatically startable internal combustion engine and which transfers power from the internal combustion engine to an axle side via a friction engagement element actuated by a fluid pressure from either of a first fluid pressure actuator driven by the power from the internal combustion engine and a second fluid pressure actuator driven by a fluid pressure source different from that for the first fluid pressure actuator, and also relates to a power transfer device including a power transfer mechanism and a control device that controls the power transfer mechanism.